The case for tuned 4 cylinder 4 strokes

[powerabout]

A whipper snipper sounds better than a 4cyl 4s

[gotboostedvr6]

There were precious few cars that could take my little weed wacker hatchback from a roll.

[WavetoWave]

I had a built K24 in my 1999 Civic hatch. 260 whp

It had very little torque under 4000 rpm.

This one is being built with that in mind, plus quite a bit more power overall than that. Should have plenty.

[Markus]

probably a dumb question but are any of the 4 strokes pushrod motors and if not,why?

Because we are in 2018.

[loop]

Because we are in 2018.

Is that really your best answer? Educate me on why it wouldnt work.
dont get me wrong i am a huge fan of OHC motors. Especially a pneumatic valve 19,000 RPM F1 motor. I know a pushrod motor wouldnt be suitable for that but why wouldnt it work for a 6000rpm, 200hp 4 cylinder? Thats a 4 stroke i would consider buying. lightweight,simple,compact,durable

[home made tunnel]

GM is the master of pushrod motors with their 4.8L, 5.3L, 6.0L, 6.2L, .... well we can just say all their V8's. Even the ZR1 is still a pushrod motor.

I'd love to see some home-tuning software come out for the 4-strokes, as the auto market has EFI Live, and other programs like that.


BY THE WAY - Anyone know of another lower unit that bolts to the 115 Pro XS?

[FMP]

Is the housing not different between the 2.07 and the other?

[FORBESAUTO]

If I had to guess why no push rod motors, it would be for emissions. You have so much more ability to control emissions and still yet make gobs of power with a wider power curve with variable dual overhead cam timing where you can control exhaust and intake cam timing independently of each other allowing you to control valve overlap. Another bonus is this time of system allows you to totally eliminate the EGR system for controling NOX emissions

[home made tunnel]

If I had to guess why no push rod motors, it would be for emissions. You have so much more ability to control emissions and still yet make gobs of power with a wider power curve with variable dual overhead cam timing where you can control exhaust and intake cam timing independently of each other allowing you to control valve overlap. Another bonus is this time of system allows you to totally eliminate the EGR system for controling NOX emissions

You know pushrod motors have variable valve timing also? My 2011 chevy Colorado with the 5.3L V8 has the variable valve timing. Some motors had the option of DOD (Displacement on Demand) which would shut 4 cylinders off and sip fuel. Unfortunately, they gave that option to the full-size trucks, and not my little Colorado (where it could have gotten 30mpg).

[FORBESAUTO]

You are correct, but with one cam you’re only advancing and retarding valve timing and not able to change overlap. Being able to change the overlap is where the advantage is.

[nitro_rat]

Is that really your best answer? Educate me on why it wouldnt work.
dont get me wrong i am a huge fan of OHC motors. Especially a pneumatic valve 19,000 RPM F1 motor. I know a pushrod motor wouldnt be suitable for that but why wouldnt it work for a 6000rpm, 200hp 4 cylinder? Thats a 4 stroke i would consider buying. lightweight,simple,compact,durable

A pushrod motor would work, but why? Pushrods are just an extra level of complexity. In a 8v 4 cylinder there are at least 16 moving parts eliminated by going OHC (pushrods and lifters). Once you go OHC, an 8v and 16v engine can share a common block. VVT is simpler, cam timing adjustments are simpler, everything is simpler when you don't have to worry about pushrods! It's all about being able to share common parts across a wide HP range of engines, lowering production costs, etc.

As Bunky Knudson (or some GM exec) said, "parts left out cause no problems and cost no money!"

[loop]

If I had to guess why no push rod motors, it would be for emissions. You have so much more ability to control emissions and still yet make gobs of power with a wider power curve with variable dual overhead cam timing where you can control exhaust and intake cam timing independently of each other allowing you to control valve overlap. Another bonus is this time of system allows you to totally eliminate the EGR system for controling NOX emissions

I dont doubt the advantages of variable valve timing and how its easier to do with OHC but its a system that adds complexity,weight,and costs. EGR valves have been on motors since the 1970's. Simple,inexpensive and effective.
Chevrolet and Dodge both are proving pushrod motors to be just as efficient and powerful as their OHC competitors. I guess they havent heard its 2018...

[FORBESAUTO]

Emissions get more and more strict each year. A push rod design can only do so much and requires more pollution devices to be added to it to try and clean it up. The DOHC with variable valve timing is able to run so much cleaner without the added pollution devices. If a manufacturer is gonna spend all this time and money in R&D, why invest it in something that’s gonna get faded out because unable to meet emission requirements 5 years down the road?

[Markus]

Is that really your best answer? Educate me on why it wouldnt work.
dont get me wrong i am a huge fan of OHC motors. Especially a pneumatic valve 19,000 RPM F1 motor. I know a pushrod motor wouldnt be suitable for that but why wouldnt it work for a 6000rpm, 200hp 4 cylinder? Thats a 4 stroke i would consider buying. lightweight,simple,compact,durable

That was a serious answer. It is not that it wouldn't work, but it would not be worth the trouble to make it work.

You don't see any clean sheet designs of pushrod engine/car combos, and very few clean sheet designs of pushrod engines. Where do you see new push rod engine designs is where they are needed for legacy packaging reasons, i.e. they are supposed to fit where another pushrod engine used to sit, i.e. at GM. There are no such packaging restrictions inside the cowling of an outboard engine.

The 7 Marine has a max rpm of 6000, which is on the low side for an outboard application. If you want to run an engine at a sustained 6000-7000 rpm, you won't go with push rods if you have a choice. Now, you can make a pushrod engine rev high, but then it gets expensive to lighten the valve train.

[WavetoWave]

Block is sleeved, large bore piston from Wiseco, Saenz connecting rods. Custom ECU by Motec. Custom 4Piston cylinder head for this application.